Dr. Cran Lucas. Shreveport-Bossier Astronomical Society & Shreveport Amateur Radio Association KG5NMF

Transcription

1 Amateur Radio Astronomy Dr. Cran Lucas Shreveport-Bossier Astronomical Society & Shreveport Amateur Radio Association KG5NMF

2 Outline Radio Astronomy Basics Radio Astronomy History Radio Astronomy Telescopes Amateur Radio Astronomy

3 Radio Astronomy Basics

4 Radio Astronomy Reveals the Hidden Universe-I We see the world around us, because our eyes detect visible light. Objects on Earth and in space also emit other types of electromagnetic radiation (EM) that cannot be seen by the human eye, such as radio waves. Radio astronomy is the study of celestial objects that give off radio waves. With radio astronomy, we study astronomical phenomena that are often invisible or hidden in other portions of the electromagnetic spectrum.

5 Radio Astronomy Reveals the Hidden Universe-II With radio telescopes, we watch: Stars turn on, shine, and die. We watch planets form from the dust and ice of solar nebula. We clock the spin of our Galaxy and thousands of other galaxies. We see the echo of the Big Bang and the Universe s very first stars and galaxies. And we spot the chemical precursors of DNA and other organic molecules floating in space.

6 Radio Astronomy Reveals the Hidden Universe-III Since radio waves penetrate dust, we use radio astronomy techniques to study regions that cannot be seen in visible light, such as: The dust-shrouded, center of our Galaxy, the Milky Way. Radio waves also allow us to trace the location, density, and motion of the hydrogen gas that constitutes three-fourths of the ordinary matter in the Universe.

7 Radio Astronomy Basics-I RF waves that can penetrate Earth s atmosphere range from wavelengths of a few millimeters to nearly 100m. These wavelengths have no discernable effect on the human eye or photographic plates, they do induce a very weak electric current in a conductor such as an antenna. Most radio telescope antennas are parabolic reflectors that can be pointed toward any part of the sky. They gather up the radiation and reflect it to a central focus, where the radiation is concentrated. The weak current at the focus can then be amplified by a radio receiver so it is strong enough to measure and record.

8 Radio Astronomy Basics-II

9 Atmospheric Opacity to Radiation

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11 Optical vs. Radio Images An optical image of the galaxy M87 (HST), a radio image of same galaxy using Interferometry (VLA), and an image of the center section (VLBA). The jet of particles is suspected to be powered by a black hole in the center of the galaxy.

12 Visible (white) vs. Radio (blue) Whirlpool Galaxy (M51)

13 Radio Astronomy History

14 Karl Jansky s Early Work-I It was the decade of 1930s and the Bell Telephone Company was having trouble with the functioning of their transatlantic service, due to static of some sort. The company asked the physicist Karl Jansky( ) to find the source of such interference. In order to track and identify the source of static, Jansky built a big rotating antenna, given the name of Jansky s merry-go-round.

15 Karl Jansky and the First Radio Telescope

16 Karl Jansky s Early Work-II The antenna was designed to receive radio waves at a frequency of 20.5MHz, and with its rotation ability it was able to locate the direction of any radio signal. After several months of studying such static, Jansky was able to classify it into three different types. The source of the first two originated from nearby and distant thunderstorms.

17 Karl Jansky s Early Work-III There was a third source of static that was somehow different. He realized that there was a pattern characterizing these signals similar to the known location of the Sun. After more accurate measurements, (the signals repeated every 23 hours and 56 seconds), Jansky concluded that the radiation came from the constellation Sagittarius (direction of the core of the Milky Way Galaxy.) Discovery was fundamental to radio astronomy.

18 Jansky s All Sky Map at 20.5MHz

19 Jansky s Discovery Jansky s discovery attracted major public attention, including front page of NY Times May 5, 1933.

20 Grote Reber& His Telescope (1937)

21 Project Ozma(1960) Organized by Frank Drake. First search for extraterrestrial radio signals. Targeted two stars: Tau Ceti Epsilon Eridani

22 Project Ozma The Beginning of Search for Extraterrestrial Intelligence (SETI)

23 What Temperature is Venus? Venus has thick cloud layers that reflect light very well. At infrared wavelengths these clouds are opaque and the temperature measured at these wavelengths is only about 225K or -55 degrees F. However measurements at radio wavelengths imply a surface temperature of about 700 K or 800 degrees F. High temperature due to thick CO 2 atmosphere and runaway greenhouse effect.

24 Radio Astronomy Telescopes

25 Ohio State University Radio Telescope: 1960s-1970s

26 Green Bank Telescope (GBT) in West Virginia 100 m Diameter

27 Arecibo (P.R.) Radio Telescope 300 m Diameter

28 VLA-Very Long Array 25 m Diameter

29 VLBA-Very Long Base Array

30 Interferometers For a single dish the resolution is λ/d, where D is the diameter of the telescope. But for an interferometer array the resolution is λ/b, where B is the maximum baseline.

31 CHIME Digital Telescope (Prototype)

32 Radio Wave Frequencies H 2 H 2 x Pi 21 cm

33 21 cm/1420 MHz Neutral Hydrogen Line

34 1420 MHz vs. 408 MHz

35 Microwave View of the Sky Cosmic Microwave Background

36 CMB Spectra

37 Amateur Radio Astronomy

38 Another SARA!

39 Radio Astronomy Amateurs

40 What can I do with a small radiotelescope? 1. Study Jupiter's noise storms. 2. Record solar flares and predict geomagnetic activity. 3. Detect a pulsar (rotating neutron star) using DSP (digital signal processing). 4. Detect stronger radio sources. 5. Look for HEPs (high energy pulses) from the galactic center. 6. Search for radio correlations to gamma ray bursts. 7. Study ionospheric scintillation and refraction. 8. Detect meteors invisible to the eye. 9. Develop a long base line interferometer. 10. Learn radio technology. 11. Learn astronomy.

41 What can I do with a small radiotelescope? 12. Find ET Greetings, Earthlings

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43 Radio Astronomy Book

44 Additional Books on Amazon

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46 lanets.com/2013/06/su mmer-project-buildradio-telescope-at.html

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48 Radio Astronomy Supplies

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50 Radio Telescope Software

51 Radio Jove

52 Radio Jove Equipment

53 Radio Jove Antenna

54 Monitoring System Example

55 Radio SkyPipe: Internet Enabled Strip Chart Recorder

56 Jupiter L-bursts Jupiter L-Bursts sound like ocean waves breaking up on a beach. Much of the L-burst structure is formed as signals travel though the interplanetary medium from Jupiter to the Earth.

57 Jupiter S-bursts Jupiter S-Bursts sound like a handful to pebbles thrown on a tin roof (or popcorn being cooked). These bursts each last for a few thousandths of a second and occur at rates as high as several dozen per second.

58 Origin of Jupiter s Emissions Radio storms on Jupiter come from natural radio lasers in the giant planet's magnetosphere. Electrical currents flowing between Jupiter's upper atmosphere and the volcanic moon Io can boost these emissions to power levels easily detected by ham radio antennas on Earth.

59 Solar Burst-I Solar Bursts received near the frequency 20 MHz often turn on rapidly and decay slowly -- looking somewhat like a shark fin on the strip chart record. These bursts can be quite strong and often last for tens of seconds. You will hear the weak galactic background noise for several seconds, followed by a Solar radio noise burst.

60 Solar Burst-II 20.1 MHz

61 Galactic Background Galactic Background signals are generated by relativistic electrons spiraling in the galactic magnetic field. The sound is a quiet hiss devoid of any interesting features like bursts or sudden changes in amplitude.

62 Pulsars Remnant of a supernova. Rotating neutron star. Radiates at visible and/or radio frequencies. Slower (0.71 sec.) Faster (0.089 sec.)

63 Radio Meteor Detection-I

64 Radio Meteor Detection-II

65 Radio Meteor Detection Setup-I FM Antenna FM Radio ( MHz) PC with Sound Card and Graphing Software

66 Radio Meteor Detection Setup-II You will need a good FM radio, an antenna, a method of recording your observation (optional), and a way of showing your data. Picking an FM Radio Station: Choose a radio station that does not broadcast in your area. For best results, you need to choose a radio station that is about 1300 km (800 mi) away. This distance usually gives the longest duration signal. But you can also detect signals reflected off meteors from stations between 200 km (400 mi) and 2100 km (1300 mi) possibly even closer or farther away. Take a provincial or state road map and with a compass, draw three circles one at 200 km, a second at 1300 km and a third at 2100 km. Look in the FM station chart for a radio station that is between the smallest and largest circles. Make sure the station transmits on a frequency different from the ones that you can receive on your FM radio at home. If you can't find a suitable station in the table, bookmark this site and go to to find one. Look for stations with the highest power possible. 100 Kilowatts is a good figure. Note the compass bearing from your location. This will be important for pointing your antenna in relation to meteor shower streams. Connect the receiver to the antenna. Connect your data logging equipment to the earphone jack of the receiver.

67 Radio Meteor Signals-I Receiver set to MHz. ICOM PCR-1000 software driven receiver. 7 element log periodic antenna pointed south. Counting software: Spectrum Lab FFT and manalyzer program.

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69 Radio Meteor Signals-II

70 Radio Meteor Signals-III

71 Data from Leonid Meteor Shower-Jodrell Bank Observatory, England, 2006 (Meteor Data: Hz vs. Time)

72 Origin of Meteors-I

73 Origin of Meteors-II

74 List of Yearly Meteor Showers (

75 Daytime Radio Meteor Showers

76 Nighttime Meteor Showers

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78 Thanks for coming

79 Are there any questions